Many conventional MEMS force and inertial sensors, such as accelerometers, magnetometers, and magnetometers, etc. include a pair of drive electrodes to which an alternating current (AC) is applied to induce a mechanical resonance in a suspended member.
In Lorentz force magnetometers, the alternating current is of a frequency tuned to induce mechanical deformation of the suspended member in a desired resonance mode by passing current through the suspended resonator so that, in the presence of a magnetic field, Lorentz forces form in the resonator inducing the resonator to mechanically deform. A number of techniques have been applied to sense the extent of deformation induced by the Lorentz forces and thereby measure the magnetic field strength. For example, deformation of the resonator is often sensed by capacitive coupling between resonator and the support, as measured by either primary drive electrodes or secondary sensing electrodes. Piezoelectric techniques have also been utilized, for example, by sensing mechanical deformation of the resonator with a piezoelectric material embedded in a resonator.
However, the conventional sensing techniques suffer from cross-talk and inherent sensitivity and other limitations. Both capacitive and piezoelectric techniques may also lack dynamic range such that many separate devices are required to conduct field measurements within different magnetic environments or where field strength varies widely and/or rapidly over time. Accordingly, there remains a need for MEMS Lorentz magnetometers that are more sensitive and/or have greater dynamic range.